Recording medium feed device

ABSTRACT

A recording medium feed device includes: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out member to send out a recording medium loaded in the recording medium feed tray, the send-out member being in contact with a top face of the recording medium while applying pressure thereto at a time of installing the recording medium feed tray; and a withdrawing mechanism to withdraw the send-out member from the top face of the recording medium in the recording medium feed tray at a time of removing the recording medium feed tray.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording medium feed device which isinstalled in an image forming apparatus such as a copying machine, aprinter or a printing press, a paper post-processing apparatus, and thelike.

2. Description of the Related Art

As a recording medium feed device used in an image forming apparatus orthe like, a device as shown in FIG. 7 has been known (for example, seeJP-Tokukaihei-7-144771A).

In FIG. 7, reference numeral 101 denotes a recording medium feed roller,reference numeral 102 denotes a separating roller to be in contact withthe recording medium feed roller 101 and connected to a torque limiter(not shown), and reference numeral 103 denotes a send-out rollerswingably supported on the rotary shaft of the recording medium feedroller 101.

Reference numeral 104 denotes a pick-up cam which brings the send-outroller 103 into contact with paper. P loaded to be accommodated in arecording medium feed tray 106, and separates the send-out roller 103from paper P.

Sheets of paper P sent out by the send-out roller 103 are separated intoone sheet by the recording medium feed roller 101 and the separatingroller 102, and conveyed to the downstream side.

Additionally, as a different mode, there has been known a recordingmedium feed device in which a recording medium feed tray and a recordingmedium feed roller are integral with a recording medium feed unitincluding a send-out roller and the like, and the send-out roller isalways in contact with paper at the time of installing the recordingmedium feed tray.

However, the device described in JP-Tokukaihei-7-144771A has involved alater-described problem, that is, a so-called “no feed” in which nosheet of paper is sent out.

Recently, paper used for image forming or the like has been varied, andimage forming has been performed on paper on one side of which an imageis formed, that is, so-called backside paper.

The backside paper is sometimes wavy due to different degrees ofshrinkage between the front and back sides of the paper. Therefore, gapsare formed between sheets when the wavy paper is loaded in the recordingmedium feed tray.

Hence, when the wavy sheets of paper are sent out while the send-outroller is in contact with and separated from the paper, gaps (air)between the sheets remain since the contacting time therewith is short.Thus, sufficient frictional force cannot be obtained between thesend-out roller and the paper on the top, thereby causing “no feed.”

Meanwhile, regarding the above-described recording medium feed tray andthe recording medium feed unit which are integral with each other, thesend-out roller is always in contact with the paper. Therefore, eventhough “no feed” can be prevented, the same number of the recordingmedium feed units as that of the recording medium feed trays arerequired. Thus, cost is increased as the number of the recording mediumfeed trays is increased.

SUMMARY OF THE INVENTION

The present invention is made in view of the above problems, and anobject thereof is to provide a recording medium feed device whichincludes an installable and removable recording medium feed tray, has asimple structure that suppresses a cost increase, and prevents “nofeed.”

As described above, the inventors of the present invention have foundout during their study on a recording medium feed device that, in astructure where the send-out roller is always in contact with therecording media, “no feed” can be prevented even when a wavy recordingmedium such as backside paper is used, since the send-out roller isalways in contact with the recording media and thus no gap is formedbetween the recording media. However, in a structure where the recordingmedium feed tray and the recording medium feed unit are integral witheach other, cost is increased even though it is easy to allow thesend-out roller to be always in contact with the paper.

The present invention has been achieved on the idea that cost can besuppressed and “no feed” can be prevented by separating the recordingmedium feed tray and the recording medium feed unit, and bringing thesend-out roller into contact with the top face of the recording media atthe time of installing the recording medium feed tray, while withdrawingthe send-out roller from the top face of the recording media at the timeof removing the recording medium feed tray in order not to displace therecording media loaded in the recording medium feed tray.

The object of the present invention can be achieved by the following.

A recording medium feed device comprises: a recording medium feed trayinstallable to and removable from a main body of the recording mediumfeed device; a send-out member to send out a recording medium loaded inthe recording medium feed tray, the send-out member being in contactwith a top face of the recording medium while applying pressure theretoat a time of installing the recording medium feed tray; and awithdrawing mechanism to withdraw the send-out member from the top faceof the recording medium in the recording medium feed tray at a time ofremoving the recording medium feed tray.

Thus, the send-out member is always in contact with the recording mediumduring installation of the recording medium feed tray. Accordingly, evenwhen a wavy recording medium having different degrees of shrinkagebetween the front and back sides thereof is fed, “no feed” can beprevented.

Moreover, by withdrawing the send-out member from the top face of therecording medium in the recording medium feed tray at the time ofremoving the recording medium feed tray, it is possible to prevent therecording medium from being displaced. Thus, the recording medium can beprevented from being torn or defectively conveyed.

A recording medium feed device comprises: a recording medium feed trayinstallable to and removable from a main body of the recording mediumfeed device; a send-out roller to send out a recording medium loaded inthe recording medium feed tray, the send-out roller being in contactwith a top face of the recording medium while applying pressure theretoat a time of installing the recording medium feed tray; a rollersupporting member to rotatably support the send-out roller; and awithdrawing member provided on the recording medium feed tray, to rotatethe roller supporting member in a direction of withdrawing the send-outroller from the top face of the recording medium in the recording mediumfeed tray in accordance with an operation of removing the recordingmedium feed tray.

Thus, the send-out roller is always in contact with the recording mediumduring installation of the recording medium feed tray. Accordingly, evenwhen a wavy recording medium having different degrees of shrinkagebetween the front and back sides thereof is fed, “no feed” can beprevented.

Moreover, by withdrawing the send-out roller from the top face of therecording medium in the recording medium feed tray at the time ofremoving the recording medium feed tray, it is possible to prevent therecording medium from being displaced. Thus, the recording medium can beprevented from being torn or defectively conveyed.

A recording medium feed device comprises: a recording medium feed trayinstallable to and removable from a main body of the recording mediumfeed device; a send-out roller to send out a recording medium loaded inthe recording medium feed tray, the send-out roller being in contactwith a top face of the recording medium while applying pressure at atime of installing the recording medium feed tray; and a recordingmedium holding member formed integrally with the send-out roller, to bein contact with the top face of the recording medium in the recordingmedium feed tray only at a time of removing the recording medium feedtray.

By providing the recording medium holding member to be in contact withthe top face of the recording medium in the recording medium feed trayonly at a time of removing the recording medium feed tray, the recordingmedium holding member being formed integrally with the send-out roller,the send-out roller is prevented from contacting with the recordingmedium. Accordingly, it is possible to prevent the recording mediumloaded in the recording medium feed tray from being displaced.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not intendedas a definition of the limits of the present invention, and wherein;

FIG. 1 is a schematic view showing a structure of an image formingapparatus;

FIG. 2 is a plan view of a recording medium feed tray 40A installed in apredetermined position;

FIG. 3 is a front view of the vicinity of a recording medium feed unit400A as viewed in the direction of the arrow A in FIG. 2;

FIG. 4 is a sectional view of the recording medium feed unit 400A takenalong the line B-B in FIG. 3;

FIG. 5 is a side view of the recording medium feed tray 40A as viewed inthe direction of the arrow C in FIG. 2;

FIG. 6 is a view showing a state where a roller supporting member 404 isin contact with the top face of recording media in the recording mediumfeed tray 40A; and

FIG. 7 is a sectional view of main part of a recording medium feeddevice according to earlier development.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinbelow, an embodiment of the present invention will be described.Note that the definitive descriptions given hereinbelow only show a bestmode of the invention, and thus should not be taken as limiting in anyway the definitions of the terms of the invention or the technical scopeof the invention.

First, with reference to FIG. 1, a description will be given of anembodiment of an image forming apparatus having a recording medium feeddevice according to the present invention.

FIG. 1 is a schematic view showing a structure of an image formingapparatus as a digital copying machine.

The image forming apparatus according to this embodiment forms a tonerimage on a recording medium by using an electrophotographic method. Theimage forming apparatus includes: an automatic original feed device 1;an image reading device 2; an image forming section 3; a recordingmedium feed section 4; a reversed recording medium discharging andre-feeding section 5; and a reversed recording medium conveying section6.

The automatic original feed device 1 includes: an original placing table11 on which an original or originals are placed; an original separatingunit 12 to separate originals placed on the original placing table 11one by one; an original conveyor unit 13 including a plurality ofrollers to convey an original separated by the original separating unit12; an original discharging unit 14 to discharge the original conveyedby the original conveyor unit 13; an original discharge table 15 onwhich the original discharged by the original discharging unit 14 isplaced; and an original reversing unit 16 including a pair of rollers toreverse an original in a double-sided copying mode.

A plurality of originals (not shown) placed on the original placingtable 11 are separated by the original separating unit 12 one by one,and then the separated original is conveyed to an image reading positionby the original conveyor unit 13.

The image reading position is placed under the original conveyor unit13, and the image of the original is read through a slit 21 of the imagereading device 2.

The automatic original feed device 1 is of a flap type. Thus, copyingcan be performed by: lifting the automatic original feed device 1 toexpose a platen glass 22; and placing an original directly on the platenglass 22.

The image reading device 2 is a device to read the image of an originaland obtain the image data. The image reading device 2 includes: anoptical system 25 to read an image of an original; and a CCD 26 toperform photoelectric conversion on the read image.

An analog signal obtained after the photoelectric conversion issubjected to A/D conversion after analog processing. Subsequently, thesignal is subjected to image processing as appropriate, and stored asimage data in a memory inside a control unit (not shown).

The image forming section 3 includes: a photosensitive drum 31 having aphotoconductive photosensitive layer as an image bearing member on thesurface thereof; a charging unit 32 which includes a charging electrodeto evenly charge the surface of the photosensitive drum 31; a laserwriting unit 33 which is an exposure unit to expose the photosensitivedrum 31 to light and form an electrostatic charge latent image on thephotosensitive drum 31; a developing device 34 to perform reversaldevelopment of the electrostatic charge latent image formed on thephotosensitive drum 31, thereby forming a toner image; a transferringunit 35 to transfer the toner image on a recording medium such as plainpaper, the transferring unit 35 including a transfer electrode; aseparating unit 36 to perform, from the back side of the recordingmedium on which the toner image has been transferred, corona dischargeby using, for example, an AC voltage or an AC-DC superimposed voltage,thereby facilitating separation of the recording medium from thephotosensitive drum 31; and a cleaning unit 37 to clean thephotosensitive drum 31 after the transfer process has been completed.

The developer accommodated in the developing device 34 is atwo-component developer whose main components are: a so-called coatingcarrier which is made by coating particulate ferrite with styrene-acrylresin and/or silicon resin; and, for example, an insulating,non-magnetic polymerized toner manufactured by a polymerizing method.

Reference numeral 38 denotes a conveyor belt to convey a separatedrecording medium, reference numeral 9 denotes a fixing device to fix thetoner transferred to the conveyed recording medium, and referencenumeral 63 denotes discharging rollers.

In this image forming apparatus, image forming is achieved in thefollowing manner. The photosensitive drum 31 is rotated by anappropriate driving unit in the direction shown by the arrow, andsequentially charged by the charging unit 32. Then, an electrostaticcharge latent image corresponding to the image of the original is formedby dot exposure by using the laser writing unit 33, and theelectrostatic charge latent image is made into a toner image by usingthe developing device 34. Thereafter, through an operation of thetransferring unit 35, the toner image is transferred onto a recordingmedium supplied by registration rollers 56 which have started to rotate.

In the recording medium feed section 4, provided are: recording mediumfeed trays 40A, 40B and 40C; recording medium feed units 400A, 400B and400C of the recording medium feed trays 40A, 40B and 40C, respectively;and three recording medium feed devices 4A, 4B and 4C each including arecording medium feed device mount (not shown) to guide the recordingmedium feed tray and hold the recording medium feed unit, and the like.In any one of the recording medium feed devices, recording mediums P areseparated into one to be fed therefrom, and conveyed toward theregistration rollers 56 through a plurality of conveyor rollers providedat the downstream side. Then, the provided recording medium P isconveyed for the transfer process.

The recording medium feed devices 4A, 4B and 4C will be detailed later.

The recording medium P on which transfer has been performed is separatedfrom the photosensitive drum 31 through an operation of the separatingunit 36. The recording medium P is then subjected to a heating andcompressing operation of the fixing device 9, and discharged to theoutside of the machine by the discharging rollers 63.

Meanwhile, the photosensitive drum 31 that has passed through thetransfer region continues to rotate, and the residual toner thereon isremoved by the cleaning unit 37. Thus, the photosensitive drum 31 isready for the next image forming.

The reversed recording medium discharging and re-feeding section 5 andthe reversed recording medium conveying section 6 have a reverselyconveying function to reverse and discharge the recording medium(hereinafter, referred to as paper) P, thereby allowing image formingonto the back side of the paper.

Next, an embodiment of the recording medium feed device according to thepresent invention will be described with reference to the drawings.

Since the basic structures of the three recording medium feed devicesare the same, a description will be given of the recording medium feeddevice 4A with reference to FIGS. 2, 3, and 4.

FIG. 2 is a plan view showing the recording medium feed tray 40A whichis installable and removable to and from the recording medium feeddevice 4A is installed in a predetermined position. FIG. 3 is a frontview of the vicinity of the recording medium feed unit 400A as viewed inthe direction of the arrow A in FIG. 2. FIG. 4 is a sectional view ofthe recording medium feed unit 400A taken along the line B-B in FIG. 3.

The recording medium feed unit 400A is provided on the main body side ofthe recording medium feed device. The recording medium feed unit 400Aincludes: a send-out roller 401 as an example of a send-out member; arecording medium feed roller 402 as an example of a recording mediumfeed member; a separating roller 403 as an example of a separatingmember; and the like.

Here, each of the rollers 401, 402 and 403 may be formed by using abelt.

Reference numeral 404 denotes a roller supporting member. The rollersupporting member 404 integrally includes: a left side plate 405; aright side plate 406; and a top plate 404A connecting the left and rightside plates. The roller supporting member 404 rotatably supports asend-out roller shaft 401A fixed to the send-out roller 401.

The left side plate 405 is held by a rotary shaft of the recordingmedium feed roller (recording medium feed roller shaft) 407 via aone-way clutch 408. The recording medium feed roller shaft 407 isconnected to the one-way clutch 408 when the recording medium feedroller shaft 407 is rotated in a direction opposite to the direction inwhich the paper P is sent out (direction shown by the arrow W in FIG.3). The right side plate 406 is held by the recording medium feed rollershaft 407 via a shaft bearing 409.

As shown in FIG. 3, the left side plate 405 and the right side plate 406integrally includes a substantially triangular recording medium holdingmembers at the left of the send-out roller 401.

The recording medium holding members are designed such that tip portions405A and 406A thereof are in contact with the top face of a stack ofpaper in the recording medium feed tray 40A only at the time of removingthe recording medium feed tray 40A. Thus, the send-out roller 401 isprevented from contacting with the top face of the stack of paper. Thedetailed description thereof will be given later.

It is preferable that the tip portions 405A and 406A are coated with amaterial of a low friction coefficient such as Teflon (RegisteredTrademark) or fluorine, or made of a low friction resin material such aspolyacetal.

The recording medium feed roller shaft 407 is rotatably supported bysupport plates 415 and 416 formed in the recording medium feed devicemount, and connected to a recording medium feed motor (not shown) via aone-turn clutch 411 which rotates in synchronization with rotation ofthe registration rollers 56 (see FIG. 1).

The recording medium feed roller 402 is held by the recording mediumfeed roller shaft 407 via a one-way clutch 410. The recording mediumfeed roller shaft 407 is connected to the one-way clutch 410 when therecording medium feed roller shaft 407 is rotated in a direction ofsending out the paper P (direction shown by the arrow W in FIG. 3).

Through an idle gear 413, a gear 412 fixed to the recording medium feedroller shaft 407 is meshed with a gear 414 fixed to the send-out rollershaft 401A.

In FIG. 3, reference numeral 421 denotes a separating roller supportingmember shaped like “C.” The separating roller supporting member 421holds the separating roller 403 via a torque limiter 420, and isrotatably supported around a supporting shaft 422 formed in therecording medium feed device mount.

Reference numeral 423 denotes a pull spring. The pull spring 423 biasesthe separating roller 403 clockwise in FIG. 3, thereby causing theseparating roller 403 to be in contact with the recording medium feedroller 402 while applying pressure thereto.

In a state where the separating roller 403 is in direct contact with therecording medium feed roller 402, or in a state where a sheet of paper Pis sandwiched between these rollers, the torque limiter 420 is slippeddue to torque exceeding a torque limit, whereby the separating roller isrotated in accordance with the recording medium feed roller 402.

In a case where two or more sheets of paper P are sent out, the torqueis within the torque limit due to friction between the sheets of paperP. Thus, the lower sheet(s) of paper P is returned to the upstream sideby the separating roller 403, whereby the lower sheet(s) of paper P isprevented from being conveyed.

Reference numerals 425 and 426 denote conveyor rollers provided at adownstream side in the recording medium conveying direction.

Reference numeral 430 denotes a bottom plate provided at the bottom ofthe recording medium feed tray 40A so as to be able to move up and down.The bottom plate 430 lifts and lowers the stack of paper in therecording medium feed tray 40A.

When the recording medium feed tray 40A is installed at a predeterminedposition of the recording medium feed device 4A, the bottom plate 430 islifted by a lifting and lowering unit (not shown) until the top face ofthe paper is detected by a recording medium detecting unit (not shown).On the contrary, when the recording medium feed tray 40A is drawn, thebottom plate 430 is lowered to a predetermined position.

The recording medium detecting unit is disposed such that the send-outroller 401 is brought into contact with the top face of the lifted paperat a predetermined position while applying pressure thereto.

Next, with reference to FIG. 5, a description will be given of awithdrawing mechanism to withdraw the send-out roller 401 from the topface of the paper, and of a releasing mechanism to release theseparating roller 403 from contact with the recording medium feed roller402, upon removal of the recording medium feed tray 40A.

FIG. 5 is a side view of the recording medium feed tray 40A as viewed inthe direction of the arrow C in FIG. 2. FIG. 5 shows a state where therecording medium feed tray 40A is going to be installed to the recordingmedium feed device 4A.

First, a description will be given of the withdrawing mechanism whichincludes a withdrawing member 440, the roller supporting member 404, andthe like.

The withdrawing member 440 is disposed at a front end portion of therecording medium feed tray 40A as viewed in the direction of installingthe recording medium feed tray 40A. The withdrawing member 440 includesinclined surfaces 441 and 442 forming a symmetric inverse V-shape asviewed in a direction perpendicular to the direction of removing therecording medium feed tray.

As shown in FIGS. 2 and 3, the inclined surfaces 441 and 442 aredesigned so as to be brought into contact with the tip portions 405A and406A of the left side plate 405 and the right side plate 406,respectively, at the time of removing the recording medium feed tray40A.

A description will be given of a positional relationship in the verticaldirection (height relationship) among the inclined surfaces 441 and 442,the tip portions 405A and 406A of the left side plate 405 and the rightside plate 406, respectively, and the top face of the stack of paper Pin the recording medium feed tray 40A.

Reference letter L denotes the top face of the paper P loaded up to themaximum number in the recording medium feed tray 40A. Reference lettersM denote the lowermost points of the inclined surfaces 441 and 442, andreference letter N denotes the uppermost point of the inclined surfaces441 and 442.

Note that the top face L herein shows a height of the paper P in a casewhere the bottom plate 430 is lowered to a predetermined position sothat the paper can be loaded.

The tip portions 405A and 406A of the left side plate 405 and the rightside plate 406, respectively, are in the same positions as viewed in thevertical direction. In addition, these positions of the tip portions405A and 406A are positions in a case where the top plate 404A of theroller supporting member 404 is in contact with a stopper 427 (see FIG.3), whereby rotation of the roller supporting member 404 is limited.

As shown in the drawing, the lowermost points M, tip portions 405A and406A, top face L, and uppermost point N are positioned in this order asviewed from a lower position to an upper position.

In accordance with an operation of installing the recording medium feedtray 40A, the tip portion 405A is moved up while being in contact withthe inclined surface 441 of the withdrawing member 440, whereby theroller supporting member 404 is rotated clockwise in FIG. 3.

After the tip portion 405A has passed through the uppermost point N, theroller supporting member 404 maintains a predetermined position(posture) at the uppermost point N due to an operation of the one-wayclutch 408 (see FIG. 4).

Similarly, in accordance with an operation of drawing the recordingmedium feed tray 40A, the tip portion 406A is moved up along theinclined surface 442, whereby the roller supporting member 404 isoperated as described above.

Next, a description will be given of the releasing mechanism including areleasing member 450, the separating roller supporting member 421, andthe like.

The releasing member 450 is disposed on the right side face of therecording medium feed tray 40A as viewed in the direction of installingthe recording medium feed tray 40A. The releasing member 450 includesinclined surfaces 451 and 452 forming a V-shape as viewed in a directionperpendicular to the direction of removing the recording medium feedtray.

When the recording medium feed tray 40A is brought to a positionimmediately before a predetermined installation position, a protrudingportion 421A (see FIG. 3) of the separating roller supporting member 421is brought into contact with the inclined surface 451 and thus lowered.

As a result, the separating roller supporting member 421 is rotatedanticlockwise in FIG. 3, and the separating roller 403 is released fromcontact with the recording medium feed roller 402. The roller supportingmember 404 in the predetermined position at the uppermost point N isrotated anticlockwise in FIG. 3, thereby being brought into contact withthe top face L of the paper in the recording medium feed tray 40A.

When the recording medium feed tray 40A is installed further, theprotruding portion 421A is moved up while being in contact with theinclined surface 452. Thus, the separating roller 403 is again broughtinto contact with the recording medium feed roller 402 while applyingpressure thereto.

Here, bringing the separating roller 403 into contact with the recordingmedium feed roller 402 is completed immediately before the recordingmedium feed tray 40A is installed to a predetermined position of therecording medium feed device 4A.

Next, a description will be given of an operation of the recordingmedium feed device 4A in such a structure.

When the recording medium feed tray 40A with a stack of paper P loadedtherein is installed, the roller supporting member 404 is rotatedanticlockwise in FIG. 3 by the withdrawing member 440. Then, the one-wayclutch 408 causes the roller supporting member 404 to maintain apredetermined position (posture) at the uppermost point N of theinclined surface 441 through.

The separating roller 403 is released from contact with the recordingmedium feed roller 402 due to an operation of the releasing member 450immediately before the installation of the recording medium feed tray40A is completed. The roller supporting member 404 is rotatedanticlockwise in FIG. 3, and the tip portions 405A and 406A are broughtinto contact with the top face L as shown in FIG. 6.

A description will be given of a positional relationship among the tipportions 405A and 406A, the outer-circumferential surface of thesend-out roller 401, and the top face of the paper.

In a case where sheets of paper are loaded up to the maximum number inthe recording medium feed tray 40A and the bottom plate 430 is loweredto a predetermined position (the state shown in FIG. 6), the tipportions 405A and 406A are in contact with the top face L, and there isa space between the outer circumferential surface of the send-out roller401 and the top face L.

In contrast, in a case where the bottom plate 430 is lifted, the topface of the paper is detected by the detecting unit, and the top face isin a predetermined position (recording medium feed position), thesend-out roller 401 is in contact with the top face of the paper, whilethe tip portions 405A and 406A are not in contact with the top face.

As is clear from the drawing, even in a case where the number of sheetsof paper is smaller than the maximum number, when the bottom plate 430is lowered to a predetermined position, the tip portions 405A and 406Aare in contact with the top face of the paper.

Returning to the description of the operation of the recording mediumfeed device, as the recording medium feed tray 40A is installed further,the separating roller 403 that has been released from contact is movedback along the inclined surface 452 of the releasing member 450 and isagain brought into contact with the recording medium feed roller 402.

After the separating roller 403 is released from contact, the tipportions 405A and 406A are slipped along the top face L until theinstallation of the recording medium feed tray 40A is completed. Arecording medium feeding operation is performed as follows after theinstallation of the recording medium feed tray 40A has been completed.

After the top face of the paper has been lifted up to a predeterminedposition by the lifting and lowering unit and the recording mediumdetecting unit, a recording medium feed start instruction is outputtedfrom a control unit (not shown) of the image forming apparatus, and theone-turn clutch 411 is operated. The recording medium feed roller 402and the send-out roller 401 start rotating, and, at the same time, theroller supporting member 404 is allowed to rotate anticlockwise in FIG.3 by rotation of the recording medium feed roller shaft 407. Thus, thesend-out roller 401 is always in contact with the top face of the paperP while applying pressure thereto.

Sheets of paper P sent out by the send-out roller 401 are separated intoone sheet by the recording medium feed roller 402 and the separatingroller 403, and then conveyed to the downstream side by the conveyorrollers 425 and 426.

When the sheet of paper P has been conveyed by a predetermined length bythe conveyor rollers 425 and 426, the one-turn clutch 411 stopsoperating.

When the trailing edge of the sheet of paper P being conveyed has passedthe send-out roller 401, the one-way clutch 410 enables the recordingmedium feed roller 402 to freely rotate in the recording mediumconveying direction, and rotation of the send-out roller 401 is stopped.Thus, the subsequent sheet of paper is prevented from being sent outfollowing the sheet of paper in front.

Next, a description will be given of an operation of the recordingmedium feed device 4A performed when the recording medium feed tray 40Ais drawn.

Upon starting drawing the recording medium feed tray 40A, the bottomplate 430 is lowered to a predetermined position. Further, theseparating roller 403 is released from contact with the recording mediumfeed roller 402 by the releasing member 450. The roller supportingmember 404 is rotated anticlockwise in FIG. 3, whereby the tip portions405A and 406A are brought into contact with the top face of the paper.

Thereafter, the recording medium feed tray 40A is drawn while the tipportions 405A and 406A are slipped along the top face of the paper. Asthe recording medium feed tray 40A is drawn further, the rollersupporting member 404 is rotated to a predetermined positioncorresponding to the uppermost point N by the withdrawing member 440,and maintains the position (posture). Thus, the drawing operation iscompleted.

Next, when the recording medium feed tray 40A is to be installed again,the recording medium feed tray 40A is moved forward without the rollersupporting member 404 receiving an operation of the withdrawing member440, since the roller supporting member 404 is already rotated andwithdrawn to the predetermined position. The separating roller 403 isreleased from contact with the recording medium feed roller 402 by thereleasing member 450, and the recording medium feed device 4A repeatsthe above-described operation.

As described above, the send-out roller is withdrawn by the withdrawingmechanism at the time of removing the recording medium feed tray, andthe send-out roller is not in contact with the top face of the recordingmedia. Thus, the recording media loaded in the recording medium feedtray can be prevented from being displaced, thereby preventing therecording media from being torn or defectively conveyed.

Moreover, the recording medium holding member of a low frictioncoefficient which is formed integrally with the roller supporting memberis allowed to be in contact with the top face of the recording mediaonly at the time of removing the recording medium feed tray. Thus, thesend-out roller, which is in general made of a material of a highfriction coefficient such as rubber, can be prevented from contactingwith the top face of the recording media, thereby preventing therecording media loaded in the recording medium feed tray from beingdisplaced.

Even when the difference between the position of the top face of therecording media loaded up to the maximum number in the recording mediumfeed tray and the position of the top face of the recording media in astate of recording medium feeding is small due to downsizing of therecording medium feed device, the send-out roller can be prevented fromcontacting with the top face of the recording media by bringing therecording medium holding member into contact with the top face of therecording media at the time of removing the recording medium feed tray.Thus, even when the recording medium feed tray is drawn at the time ofpaper jam in a state where recording media are loaded up to the maximumnumber, the recording media can be prevented from being displaced.

Moreover, the send-out roller is always in contact with the top face ofthe recording media during installation of the recording medium feedtray. Thus, even when the recording media are wavy due to differentdegrees of shrinkage between the front and back sides of the respectiverecording media such as a sheet of paper already having an image formedon one side thereof (backside paper), and when there are gaps betweenthe recording media, the gaps are eliminated and friction necessary forsending out the recording medium on the top is generated. Thus, aso-called “no feed,” where no recording medium is sent out, can beprevented.

The entire disclosure of Japanese Patent Application No. Tokugan2004-039555 filed on Feb. 17, 2004 including specification, claims,drawings and summary are incorporated herein by reference in itsentirety.

1. A recording medium feed device, comprising: a recording medium feedtray installable to and removable from a main body of the recordingmedium feed device; a send-out member to send out a recording mediumloaded in the recording medium feed tray, the send-out member being incontact with a top face of the recording medium while applying pressurethereto at a time of installing the recording medium feed tray; and awithdrawing mechanism to withdraw the send-out member from the top faceof the recording medium in the recording medium feed tray at a time ofremoving the recording medium feed tray.
 2. The feed device of claim 1,further comprising: a recording medium feed member provided at adownstream side of the send-out member in a direction of sending out therecording medium; and a separating member to be in contact with therecording medium feed member while applying pressure thereto.
 3. Thefeed device of claim 2, wherein the recording medium feed member is arecording medium feed roller, and the separating member is a separatingroller.
 4. The feed device of claim 1, wherein the send-out member is asend-out roller.
 5. The feed device of claim 1, wherein the withdrawingmechanism moves the send-out member to a withdrawing position which isaway from the top face of the recording medium in the recording mediumfeed tray in accordance with an operation of removing the recordingmedium feed tray, and moves the send-out member from the withdrawingposition to the top face of the recording medium in the paper feed trayin accordance with an operation of installing the recording medium feedtray.
 6. The feed device of claim 2, further comprising a releasingmechanism to release the separating member from the contact with therecording medium feed member in accordance with an operation ofinstalling the recording medium feed tray.
 7. The feed device of claim6, wherein the releasing mechanism comprises a releasing member providedon the recording medium feed tray, to release the separating member fromthe contact with the recording medium feed member, and the releasingmechanism releases the separating member from the contact with therecording medium feed member by using the releasing member at the timeof removing the recording medium feed tray.
 8. A recording medium feeddevice, comprising: a recording medium feed tray installable to andremovable from a main body of the recording medium feed device; asend-out roller to send out a recording medium loaded in the recordingmedium feed tray, the send-out roller being in contact with a top faceof the recording medium while applying pressure thereto at a time ofinstalling the recording medium feed tray; a roller supporting member torotatably support the send-out roller; and a withdrawing member providedon the recording medium feed tray, to rotate the roller supportingmember in a direction of withdrawing the send-out roller from the topface of the recording medium in the recording medium feed tray inaccordance with an operation of removing the recording medium feed tray.9. The feed device of claim 8, further comprising: a recording mediumfeed roller provided at a downstream side of the send-out roller in adirection of sending out the recording medium; and a separating rollerto be in contact with the recording medium feed roller while applyingpressure thereto.
 10. The feed device of claim 8, wherein the rollersupporting member is held by a rotary shaft of the recording medium feedroller via a one-way clutch to which the rotary shaft is connected whenthe rotary shaft is rotated in a direction opposite to a direction ofsending out the recording medium.
 11. The feed device of claim 10,wherein the withdrawing member rotates the roller supporting memberaround the rotary shaft via the one-way clutch in the direction ofwithdrawing the send-out roller from the top face of the recordingmedium in the recording medium feed tray in accordance with theoperation of removing the recording medium feed tray.
 12. The feeddevice of claim 9, further comprising a releasing mechanism to releasethe separating roller from the contact with the recording medium feedroller in accordance with an operation of installing the recordingmedium feed tray.
 13. The feed device of claim 12, wherein the releasingmechanism comprises a releasing member provided on the recording mediumfeed tray, and the releasing mechanism releases the separating rollerfrom the recording medium feed roller by using the releasing member at atime of removing the recording medium feed tray.
 14. The feed device ofclaim 13, wherein the releasing mechanism releases the separating rollerfrom the recording medium feed roller by moving a roller supportingmember supporting the separating roller.
 15. A recording medium feeddevice, comprising: a recording medium feed tray installable to andremovable from a main body of the recording medium feed device; asend-out roller to send out a recording medium loaded in the recordingmedium feed tray, the send-out roller being in contact with a top faceof the recording medium while applying pressure at a time of installingthe recording medium feed tray; and a recording medium holding memberformed integrally with the send-out roller, to be in contact with thetop face of the recording medium in the recording medium feed tray onlyat a time of removing the recording medium feed tray.
 16. The feeddevice of claim 15, further comprising: a recording medium feed rollerprovided at a downstream side of the send-out roller in a direction ofsending out the recording medium; and a separating roller to be incontact with the recording medium feed roller while applying pressurethereto.